Yahoo says it may write down all of Tumblr's value

Yahoo CEO Marissa Mayer's $1.1 billion deal for Tumblr may end up being a bigger bust than anyone thought.

The Internet company disclosed in an SEC filing that it is "reasonably possible" that the it could write down all of the remaining value of micro-blogging site Tumblr, which it acquired in 2013.

That would come after Yahoo took a $230 million goodwill-impairment charge for Tumblr for the fourth quarter of 2015. On the company's balance sheet, Tumblr represented $519 million of its remaining $808 million goodwill balance as of Dec. 31, 2015.

"Given the partial impairment recorded in our Tumblr reporting unit in 2015, it is reasonably possible that changes in judgments, assumptions and estimates we made in assessing the fair value of goodwill could cause us to consider some portion or all of the remaining goodwill of the Tumblr reporting unit to become impaired," Yahoo said in a 10-K filing Monday.

The disclosure comes with Yahoo's future in flux. The company is in the process of engaging with prospective buyers, reported to include Comcast, AT&T, Verizon and Time Inc., as it cuts back operations with a 15% reduction in workforce.

Yahoo has struggled to turn Tumblr, which has around 550 million monthly users, into a strong revenue-generating business. The goal was to bring a much-needed social network to Yahoo, whose core business of display advertising and search continues to deteriorate. Tumblr has launched advertising units and added video, to compete with services like Facebook's Instagram, but Yahoo said the unit could face future declines.

Drops in Tumblr's market share "could negatively impact the estimated future cash flows and discount rates used in the income approach to determine the fair value of the reporting unit," Yahoo said in the filing, which "could result in an impairment charge in the foreseeable future."

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